Mold for concrete pipe.



P. N. GRONHOLM.

y MOLD FOR CONCRETE PIPE.

APPLIGATION FILED JUNE 7. 1911t 1,103,270. Patented July 14,1914,

2 SHEETS-SHEET l.

llllI/lllllIIllllIII/n'lli n flllllllll.' IIIIIIII. \\\\\\\\\\\\\\\Y Wbt/Twig@ 17 v THE NORRIS PETERS CO., PHOTO-LITHO.. WASHINGTON, D, C.

F. N'. CRONHOLM.

MOLD POR .GONGRETE PIPE.

APPLICATION' FILED JUNE 7, 1911.

Patented July 14, 1914 THE )forumsA 15E-rens, co., PHOTO-LITHQ. WAsiHN-rolv, n c,

FREDERICK N. GRONI-IOLCMI, OF SUNNYSIDE, WASHINGTON.

MOLD FOR CONCRETE PIPE.

Specieaton of Letters Patent. l Patented July 14:, 1914.

Application filed J une 7, 1911. Serial No. {531,738} I To all whom t may concern:

Be it known that I, FREDERICK N. CRON- HoLM, a citizen of the United States, residing at Sunnyside, in the county of Yakima and State of Washington, have invented a new and useful Mold for Concrete Pipes, of which t-he following is a specification.

This invention has reference to improvements in molds for concrete pipe, and is designed more particularly for the manufacture of concrete pipe of comparatively small diameter, the object of the present invention being to provide a mold of such construction that concrete pipe' may be economically formed of wetmixtures and eliminating certain of the objectionable features heretofore inherent in the manufacture of concrete pipe of small diameters in molds as ordinarily constructed.

It is customary to manufacture concrete pipe of small diameter with what is commonly known as a dry concrete mixture, wherein there is so small a percentage of water that the mixture when ready for tamping contains about the same amount of moisture as does damp earth and is, therefore, very porous. Such a mixture is termed a dry mixture as compared with the wet mixtures which because of the greatamount of water present have received the name of wet or sloppy mix.

rlhe dry or damp mixture is extensively used for various reasons, as, for instance, the output is governed by the amount which can be mixed and not by the size of the plant, the forms can be removed as soon as filled, and, therefore, may be used over again immediately, the forms require neither oiling nor cleansing, and the economy with which they may be made. However, a pipe formed of the so-called dry concrete is very orous and the manufactured product is so frail that the percentage of breakage due to handling and shipping is large. Furthermore, it will not withstand a hydraulic pressure greater than a ten or fifteen foot head, depending on the diameter of the pipe,

so that for greater heads iiumes and wooden i pipes replace pipes made of the damp concrete mixture, but such flumes and wood pipe are of only temporary character. Furthermore, the damp or dry concrete mixture does not permit the use of reinforcements. Concrete pipe made of the wet mixture is greatly superior in strength and admits of the use of reinforcements.l Again, with a wet mix a surface far superior to that obtained from dry concrete may be secured, so that pipe may be made of materially smaller diameter, and because of the comparatively small friction, may still furnish as large a quantity of water as a larger pipe made of the dry mix, this resulting in a saving of material, and, furthermore, the pipe so made 1s `lighter to handle owing to the reduced diameter. `With the wet mix a coarser aggregate may be used in the manufacture of the pipe, whereby there is a saving in the quantity of cement necessary of nearly fty per cent. Because of the greater strength of the pipe, the sections may be of greater length.

With the present invention, and because of the lighter form of the pipe with superior strength over pipe made by the dry concrete method, the cost per foot of pipe laid in place need not be much if any greater than that of pipe made by the dry process, while the actual strength of the pipe is much greater. Of course,small pipe can be made of wet concrete by the use of forms now on the market, but the manufacture is prohibitive because ofthe high cost of the forms and the necessity of having a great number of the forms, since they must be left in place until the concrete has solidified suliiciently, and, furthermore, the breakage due i to the removal of the forms is comparatively sary is not of great moment as compared with the ordinary forms used in the wet concrete process, so that the far superior pipe made from wetconcrete over that made from dry concrete can be produced at about the same price as pipe made from dry concrete. Moreover, the forms of the present invention greatly facilitate and simplify the operation of molding and to a 'commensurate extent cheapen the cost of manufacture.

The invention will be best understood from a consideration of the following detailed description, taken in connection with the accompanying drawings forming a part of this specification, with the understanding, however, that the invention is susceptible of various changes and modifications and that the drawings while showing practical emy bodiments of the inventio'mby noV means' close all the practicall embodiments which the invention may assume.

In the drawings, Figure 1 is a longitudinal diametric section of a form constructed in accordance with the invention. Fig. 2 is a plan viewof the form with' the filling: hopper omitted. Fig. 3 is a crosssectionof a portion of the outer form at thedivisionline.l Fig: 4 is alongitudi-na'l'sectionaof` a portion of a. form showing a construction of lining for largemolds. Fig. 5 is a longitudinalidiametric section of the upper end ofy a form constructedy in accordance .with the present invention, anddrawn to alarger scale than Figs. 1y andI 2, the showing of Fig. 5 being-.of a slightly modified 4form-of the invention. Fig. 6 is adiametric section'of a portion ofthe lower .end of ithe formfa'lso showing a modicationof the invention.

, Each form is composed of outer and inner members,V the formfbeingy designed: forl the castingofpipe sections. Y The outerform is made up of a ser-ies of bars or slats 1,-and the inner `form of a like series ofbars or slats 2, each bar or slat 1 taperngfrom a wide portion 3 toward reach endyandreach bar or slat 2 tapering from alike wide pors tion 11 toward-each fend, and in each instance in a circular series.

the wide portion is shown as'being'nearer one end oftherespective barior .slat than the othery end. The taper-portion ofthe respectivebar or slat is confined to one ylongitudinal edge, while the other `edge is straight or shaped in conformity with the respective outer or inner surface of the pipe section to be formed. Ars the pipe sections are usually straight, it will be assumed for convenience of description -that theimold is to ybe'used for the purposeof making straight pipe of even thickness' 4throughout or to points adjacent the ends. I 1

The slats 1 and 2 are generally segmental in cross section and the slats lare joined at lthe ends-by bands 5, 6, respectively, both bandsy being broken at one point so that' the slats may be spreadrout or assembled These bands 5 and 6 may loe-made of leather or other flexiblelmaterial, andeven in some vcases of flexible metal. The straight edges of the slats 1 are covered by a web 7 of rubber, preferably in the form "of rubber cloth, so that thefsurface of the web-away from the slats 1 is a waterproof surface non-adherent tov-wet cement. 1

Enough of the slats 1 are employed to form a circular :series of the required diameter with the slats close together,and when the outer member lof the mold is assembled the slats are substantially radial. The rubber web 7 is; divided longitudinally, so that the louter. member :of: the mold may be opened, and, iffdesired, laid .fiatyandwhen the outer member of the mold is assembled in4 circular form, the edges'of'the webV -7 are brought substantiallyA together, bothl edges yprojecting beyond adjacent ones ofthe slats1.

The free ends of the web 7 are secured to .strips 8, 9,'respectively, which together may be of a thickness to substantially fill the space between/the `end slats 1 of theseries,

but thefree edges -of the web 7 are so secured to the strips 8 and 9 that where these edges meet lwill beI in overlying relation.l to the edgefof one of the strips,say the strip 8, in such manner tha'tthejoint will not leak cement, since it is backed up by such strip 8, although -`one yof the ends ofthe web is not directly connected -to such strip 8.-

'zT-he slats 2are connectedat the end byk form of rubberv cloth, andA this sleeve 12,-: as

well as the web 7, may, if desired, be backed up or reinforced in any suitablefmanner.

lThe coremade up lof the slats' is expanded by.means ofinteriorlyia'pplied hoops 13, 14C, respectively, while the .exterior portion of the mold is contracted by eXteriorly applied hoops 15, 16, respectively, these hoops being ofproper size -to engagef-those'tapered porl tions of the vrespective slats 1 and 2 between .the wide portionsthereofiand thenarrow ends secured to the respective bands 5 and 10. The-'hoops y18, 16 maybe made of metal of suitable size and preferably are made of metalvof substantially circular cross ysection as facilitating' both the application'and removal of the hoops.

ln the structure shown Vin Fig. 1 there is provided a basic ring 17, i-t .being customary tof'set Athe mold upright, and introduce the mixzat the top." This-"ring is formed with Van annular'peripheral foot l18 and with reslats 1 resting on the ledge 18 and the lower `spective ledges 19 and'20 for lsupporting the Sslats 1- and 2,-the lowernarrow ends of the narrow ends of the slats 2 resting on the ledge 20. The ring is formed with annular shoulders 21, 22, respectively, which limit the=inward movementof the outer member ofthe mold and the'outward movement of the core at the lower ends thereof, and where avbell endwis to be made the shoulder .2Q/:may be formed on. the ywinner edge of an annular flange 23. shap'ed to 'forman'an- 'nularrgroove' constituting the bell of the cor- .responding end of the pipe. The upper end of the outer member of the mold has applied thereto a ring 24 which may be provided with an outwardly flaring flange 25, the ring 24 limiting the inward movement of the upper ends of the slats 1. The upper ends of the slats 2 are encircled by a ring 26 which may extend to some distance above thel tops of the slats, and this ring determines the outward movement of the corresponding ends of the core slats. The ring 24 with its flaring flange 25 is adapted to receive an annular hopper 27 and the upper end of the ring 26 is provided with a cover plate 28.

When an exceedingly long section of pipe is to be made, it is advisable to use a rubber sleeve or jacket 12 in two or more sections, as indicated at 12CL and 12b in Fig. 4, and it is of course apparent that the whole mold may be made in two or more longitudinally disposed sections when the mold is of such a length that the handling of long sections would be troublesome. It is not necessary that the straps 5, 6, 10 and 11 be fastened to the taper edges of the slats 1 andv 2, for these straps may be inset in kerfs cut in the corresponding ends of the slats, as indicated at 5a and 10 in Fig. 5, and 6a and 11a in Fig. 6. Again, the ring or footing 17 may be omitted and the bottom ends of the outer member of the mold and the core may rest upon a suitable flat surface and the space between the web 7 and sleeve 12 may receive a layer 29 of sand, upon which is placed a ring 30 of heavy paper or cardboard, and in the case of the formation of a bell at the end of the pipe, a suitable shaped ring 31 of rubber or having a facing of rubber is lodged upon the ring 30 and against the sleeve or jacket 12.

It is to be observed that the mold is of skeleton type and is not only light, but may be cheaply constructed, so that a comparatively large number of such molds may be made at the cost of a single heavy metal mold, such as is commonly employed in concrete pipe manufacture. making the sleeve or jacket 12 of rubber or of a rubber faced material without joint or lap, the interior of the pipe is finished smooth, it not being material as to the outer portion of the pipe, for it is the inner wall of the pipe with which water or other fiuid is brougl'it into contact, and because of the extreme smoothness of the inner wall of the pipe due to molding the cement against the rubber surface, the frictional resistance is reduced to a. minimum and consequently a pipe of considerably smaller diameter than the pipes as ordinarily made may be employed to conduct the same amount of fiuid, such as water. Moreover, the rubber faced sleeve obviates the necessity of either oiling or cleaning the molds.

When the mold has been set up, the outer portion of the mold may be centered with relation to the core with sufficient accuracy Furthermore, by

by pushing it in one direction or the other to cause the space between the innerwalll of the outer sect-ion of the mold and the outer wall of the core to be of substantially even thickness throughout, or the tWo walls defining the molding space are in substantially concentric relation one to the other.

The wet mix is introduced into the hopper 27 and flows into the molding space, being prevented from falling into the interior of the hollow core by the cover 28. When the mold is approximately full, the ring 24 may be removed and the filling completed, leaving thecorresponding end of the pipe in a finished condition. lWhen the cement mix has sufficiently set the hoops 13, 14, 15 and 16 may be removed permitting the core to collapse, so that its diameter is reduced and it may then be readily removed, lwhile the outer portion of the mold may be separated at the junction point and readily removed from the exterior of the molded pipe. Now

the sleeve or jacket 12 being of a flexible cement mix engages being non-adherent to the wet mixture, require no cleaning and may be immediately again used as soon as they are removed from the set pipe previously cast. The web 7 is fastened to the strips 8 and 9 only, and therefore the slats 1 ma. be removed promptly for the web 7 will hold the material until set sufliciently. The ring 26 is to remain in the end of the pipe section to enter the bell end of the next section in order in a line of laid pipe sections.

`What is claimed is 1. A mold for the manufacture of concrete pipe, comprising expansible and collapsible inner and outer members, each composed of a series of slats each tapering along the edge remote from the mold chamber, with flexible bands joining the ends of the slats of each member together, hoops adapted to the taper edges to expand the inner member and contract the outer member, and limiting means for the respectiveends of the mold members, constructed to operate in opposition to the hoops.

2. A mold for manufacturing concret-e pipe, comprising expansible and collapsible inner and outer members each composed of a series of slats tapering along the edges remote from the mold chamber, with flexible bands-at the ends joining the slats of each i member together and 4having their continuity broken topermit the laying out fiat, of the mold members, hoops adapted to the tapered tract the outer'member, and limiting means' edges toexpand the inner member and cona series ofvslats each tapering along the edge i remote fromthe mold chamber, with flexible bands joining the ends of the slats of each member together, hoops adapted tothe taper edges to expand the inner memberand contract'the outer member, and limiting means for therespective ends of the mold members constructed to operate in opposition to the hoops, said limiting means comprising a basic member with shoulders for the lower ends of the respective mold members, and rings for theupper ends of the respective mold members'. i

4l. A'mold for the manufacture of concrete pipe comprising expansible and collapsible inner and outer members, each composed of a series of slats each tapering along the edge remote from the mold chamber, with flexible bands joining Vthe ends of thevslats of each member together, hoops adapted to the taper edges to expand the inner member and conn tract the outer member, and limiting means for the respective ends of the mold members constructed to operate in opposition to the hoops, said limiting means comprising a basic member with shoulders for the lower ends of the respective mold members, and rings for lthe upper ends of the respective mold members, the limiting ring for the upper end of the inner mold ymember being elongated axially to project therebeyond and to be retained by and extend beyond the correspondingend of the molded pipe section and co-nstitute an entering member for the bell end of a matching pipe section.

5. A mold for the manufacture of concrete pipe comprising expansible and collapsible inner and outer members each composed of a series of slats tapering along the edge remote fro-m the mold chamber, retaining means for the respective ends of the mold members for determining the extent f of expansion and'contraction, hoops adapted to the tapering edges to expand the inner member and contractfthe outer member, a sleeve of fabric nonadherent to concrete and constructed to envelop the inner member, and another sleeve of fabric nonadherent to concrete and constructed 4to line the inner wall of the outer member.

6. A mold for the manufacture of concrete pipe comprising expansible andcollapsible inner and outer members each comtaining means for the respective ends ofthe mold members for determiningfthe extent of ex ansion and contraction hoo s `adapted to the tapering edges to expand the linner member and contract the outer member, a sleeve of fabric nonadherent to con# crete and constructed to envelop the inner' member, and anothersleeve of fabric nonadherent to concrete and constructed tol line t-he inner wall of lthe outer vmember, the secondnamed sleeve vof*fabric.having its continuity broken and provided at themeetl ing edges with slats adapted to lodge between adjacent slats of the7 outer inoldl member. y f

7. Aniold for the manufacture of concrete pipe comprising an expansible and collapsible coreand an exterior contractible mold member,each made up of a connected series of slats with those of the'core tapering on the inner edge from one end toward fthe other and'tliose on the outermold member tapering on the outer edge from one end toward the other, ylimitingdevices for the endsof the respective mold members, and hoops adapted to the taper edges of the mold ymembers to enter the core from conti'actible core formed of longitudinally disposed' slats connected at opposite ends by flexible connecting bands, an outer mold member comprising longitudinally disposed slats joined 'at the opposite ends by flexible connecting bands, thev inner edges of the slats of the core and the outer edges of the slats of the outer member tapering from one end toward the other, hoops adapted to? the taper edges of the core and outer member, a shouldered ring for receiving' the lower ends of the core and outer member, respectively, and constructed to serve vas a limiting member therefor in opposition to the action of the hoops, a ring adaptedto the upper, inner edge of the outermember, and a ring adapted to the upper, outer edge of the core, and constructed to serve as limiting members therefor in opposition to the ijic iis

izo

contractible core formed of longitudinally disposed slats connected Vat opposite ends' by flexible connecting bands, the inner edges of the slats .of the core and the outer edges of the slats of the outer member tapering from onev end toward the other, hoops adapt ed to the taper edges of the core and outer .member, a shouldered ring for receiving the loWer ends of the core and outer member, respectively, and constructed to serve as a limiting member therefor in opposition to the action of the hoops, a ruig adapted to the upper inner edge of the outer member, ,and a ring adapted to the upper, outer edge of the core, and constructed to serve as limiting members therefor in opposition to the hoops, the core being provided With a removable flexible fabric sleeve nonadherent to concrete, and the outer mold member being provided With a similar sleeve having its circumferential continuity broken and provided With slats at the meeting edges With one edge of the sleeve extending beyond the respective slat a dista-nce to engage the other slat.

10. In a mold for the manufacture of concrete pipe, a mold member composed of a series of slats joined at thev ends by flexible bands each having its continuitv broken to permit laying out of the series of slats and its assemblage into inclosing relation to a mold chamber, and a lining for the mold member comprising a sheet of fabric nonadherent to concrete, said sheet of fabric having its circumferential continuity broken and at the edges provided With slats adapted to lodge between the meeting edges of the said mold member vvhen in operative position.

In testimony, that I claim the foregoing as my oWn, I have hereto aflixed my signature in the presence of tWo Witnesses.

FREDERICK N. CRONI-IOLM.

Witnesses:

R. A. TRAIL, SUSAN E. CHARLES.

Copies of this patent may be obtained for ve cents each, by addressing the Commissioner of Patents, Washington, D. C. 

